CNN later confirmed an incident took place to Talking Points Memo but refused to give specifics.

“CNN can confirm there was an incident directed at an employee inside the Tampa Bay Times Forum earlier this afternoon," the statement said. "CNN worked with convention officials to address this matter and will have no further comment."

On Wednesday the convention released a statement to CNN saying: “Two attendees tonight exhibited deplorable behavior. Their conduct was inexcusable and unacceptable. This kind of behavior will not be tolerated."

The reported incident will be embarrassing for the Republicans as the party's candidate for president, Mitt Romney, trails President Obama by a rather large margin among African American voters.

A NBC News/Wall Street Journal poll published last week showed Obama had the support of 94%, while Romney had the backing of 0%.

Romney was formally nominated as the Republican candidate on Tuesday and is due to address delegates on Thursday evening.